The momentum that ended in Trent Lott's resignation yesterday as the Senate majority leader did not, primarily, come from the traditional behemoths of the US media - the New York Times, the Washington Post and the main TV news networks.

Instead, the controversy has proved a defining moment for the vibrant online culture of weblogs - nimble, constantly updated, opinion-driven internet journals, freed from many of the constraints of the established media.

Mr Lott's incendiary comments on December 5 went unmentioned in the Washington Post's account of Senator Strom Thurmond's 100th birthday party. They were not picked up by the New York Times, which defines the news in the US, until December 10.

In the interim, writers on numerous weblogs, or "blogs", were condemning the remarks - and swiftly uncovering evidence of a pattern in Mr Lott's public pronouncements of indulgence towards the racist policies of the Old South.

Josh Marshall, whose blog Talking Points Memo (www.talkingpointsmemo.com) has led the charge, said: "This was a story that the [established] press in DC was very well suited to miss, because even for people who wish it were otherwise, it's been understood for a long time that you've got various conservative Republicans who go in for this kind of stuff.

"Also, the way daily journalism works, a story has a 24-hour audition to see if it has legs, and if it doesn't get picked up, that's it."

Blogs, by contrast, can keep a story from expiring. Mr Marshall dredged up an interview Mr Lott had given to Southern Partisan, a magazine widely accused of promulgating racist views.

Another leftwing blogger, Atrios (www.atrios.blogspot.com), found a 1948 Thurmond campaign document telling voters that electing his rival, Harry Truman, would mean "anti-lynching and anti-segregation proposals will become the law of the land and our way of life in the South will be gone forever."

But the uproar united those from the left with the neo-conservatives such as Andrew Sullivan (www.andrewsullivan.com).

"Part of the genuine moral outrage for the younger crowd is that it really is simply unthinkable to us that anyone, even jokingly, perhaps especially jokingly, could have a good word to say for the presidential campaign of Strom Thurmond," Mr Sullivan wrote on his site yesterday.